1. Field of the Invention
The present invention relates to warning light systems and particularly to light assemblies for installation on vehicles, especially emergency and other public service vehicles.
2. Description Of The Prior Art
Lighting systems for mounting on the exterior of police and other public service vehicles have long been known in the art. Exterior mounting of such lighting systems is generally preferred in order to enhance visibility. A warning light mounted above the roof of an emergency vehicle may be more readily seen than a light mounted below the vehicle roof line or within the vehicle and such exterior mounting affords the possibility of the emitted light being seen from any direction. Exterior mounting also minimizes the possibility that the light produced by the lighting system will interfere with the vision of the vehicle operator. Further, an exterior mounted lighting system may be designed to perform illumination functions which would otherwise have to be accomplished manually and thus an exterior mounted light assembly may free the vehicle operator's hands and attention for other tasks.
The most popular form of exterior lighting system for emergency vehicles is the lightbar which spans, but is spaced slightly above the top of the vehicle and is supported by the top and clamped to the vehicle rain gutters. Lightbars are desirable because of their ability to provide a wide variety of types of illumination, because they can be installed easily and without major vehicle modifications, and because they can be removed from the vehicle if necessary or desirable. Previously available lightbar assemblies have, however, been characterized by a number of inherent deficiencies. A major deficiency of the prior lightbars has been their impact upon vehicle fuel consumption. Because of their comparatively large frontal area, prior lightbar assemblies had comparatively poor aerodynamic characteristics. Another deficiency of prior lightbar assemblies resided in their inflexibility of design. That is, the construction of prior lightbar assemblies did not permit the user to dictate the characteristics of the device but rather required the user to purchase from a limited number of "standard" models. Yet another disadvantage of previously available lightbar assemblies has been their generally decreased visibility in bright sunlight because of "wash-out" effect resulting from light entering the assembly via the transparent or translucent upper side of the molded plastic housings thereof. Attempts to overcome this "wash-out" effect by applying an opaque coating to the interior of upper portions of the outer housings have not been entirely successful. Still another deficiency of prior lightbar assemblies was their comparatively heavy weight resulting from the type of construction which was required to preven the assembly from sagging in the middle. Prior lightbar assemblies have often also been difficult to service. With regard to servicing, some prior art lightbar assemblies must be disassembled for servicing and any inoperative components painstakingly removed and repaired and the device then reassembled.
Another deficiency in known lightbars is the difficulty of providing full warning light effectiveness on the sides of the lightbar, simultaneously with operation of the so-called "alley" lights.